Chikila gaiduwani, Kamei, Rachunliu G., Gower, David J., Wilkinson, Mark & Biju, S. D., 2013

Kamei, Rachunliu G., Gower, David J., Wilkinson, Mark & Biju, S. D., 2013, Systematics of the caecilian family Chikilidae (Amphibia: Gymnophiona) with the description of three new species of Chikila from northeast India, Zootaxa 3666 (4), pp. 401-435 : 425-429

Chikila gaiduwani sp. nov.

( Figures 1 , 2 , 3 D, 5D, 6D, 9B and 12; Tables 1–6)

Chikila sp.: Kamei et al. (2012) (in part)

Holotype. ZSI A11543 , female, collected 12 June 2009, by RGK & SDB from Teobronggre (Theobongiri) Coffee Garden (25.61750 N, 90.23639 E; 519 m asl), Teobronggre, Tura, West Garo Hills district, Meghalaya, India.

Paratypes. BNHS 5500, ZSI A11541, ZSI A11542, collected with the holotype; BNHS 5505, collected 13 June 2009 from Teobronggre 3; BNHS 5504, collected 30 July 2009 from Silchol 5; BNHS 5495, 5498, collected 30 July 2009 from Silchol 4; BNHS 5502–5503, ZSI A11537 collected 31 July 2009 from Silchol 2. The localities Teobronggre 3, Silchol 2, Silchol 4, Silchol 5 are within a radius of ca. two km of the holotype locality. All specimens collected by RGK & SDB.

Referred specimens. ZSI A11536, collected 10 May 2008 by RGK & SDB from Anogiri 2; BNHS 5497, SDB.DU 1406, collected 13 May 2008 by RGK & SDB from Rome; SDB.DU 1560, collected 14 June 2008 by DG, MW, RGK & SDB from Barkha forest; BNHS 5508, collected 19 June 2008 by DG, MW, RGK & SDB from Umjarasi 1; BNHS 5507, collected 14 June 2009 by RGK & SDB from Dwarka; BNHS 5506, collected 21 June 2009 by RGK & SDB from Asanang; BNHS 5499, collected 14 July 2009 by RGK & SDB from Kanchiguli 1, Garbhanga; SDB.DU 1535, collected 31 July 2009 by RGK & SDB from Silchol 2.

Diagnosis. A Chikila that differs from all congeners in its distinctive bicoloured patterning in adults with a rather abrupt transition at just above halfway down flank (vs. more unicoloured in C. alcocki , moderately bicoloured with a fairly gradual transition from darker dorsum to paler venter in C. darlong and C. fulleri ), head that is broadly rounded anteriorly in dorsal view (vs. moderately broad in C. alcocki , pointed in C. darlong , moderately pointed in C. fulleri ) and relatively large choanae (vs. choanae narrow in C. alcocki , small in C. darlong and C. fulleri ).

Description of the holotype ( Figures 9 B and 12). Some morphometric and meristic data are in Tables 3D and 4 . In good condition; an incision midventrally extending for ca. 25 mm from ca. 40 mm anterior to vent; one posterior scale pocket open dorsally. Female with small, unyolked ova, largest measuring 1.1 x 0.7 mm.

Body slightly dorsoventrally flattened throughout, slightly less so and narrower on posterior half; L/W = ca. 36. In dorsal view, sides of head straight, converging steadily to level of TAs, rapidly between TAs and snout tip. In lateral view, top of head straight, upper lip concave with apex slightly closer to level of eye than TA, lower jaw approximately same height as upper jaw at CM. In ventral view, lower and upper lips much more blunt than ST. Eyes not visible. TAs very slightly elevated, visible dorsally and ventrally, lie just below (touching) imaginary lines between nares and CMs. Nares just visible ventrally and dorsally. Teeth of inner series smaller, tips barely visible beyond gingivae; VP series forming gentle (not angulate) arc anteromedially; projection of snout anterior to front of mouth approximately 1.75 times distance between VP and PM series anteriorly. Choanae subcircular, valves visible, separated from each other by approximately the width of one choana. Substantial gap between anterior tip of tongue and IMs (and laterally between toungue and OMs). Narial plugs flap-like, not extending beyond tongue margin, separated from body of tongue by deep grooves, except anteriorly. Paired paramedian longitudinal grooves extend posteriorly from a short distance behind plugs.

Nuchal region more massive than adjacent body; much more massive than back of head. NG1 and NG2 completely encircling body, former bending slightly anteromedially on dorsum; C2 with two TGs, one centrally almost across width of dorsum of C2, second faint, short, between main TG and NG2. First few (ca. seven) AGs complete middorsally, mostly incomplete or very faintly marked behind this until posterior third where again complete; AGs mostly incomplete or poorly marked ventrally along midline, some complete posteriorly. First ca. 11 AGs slightly oblique (anterodorsal to posteroventral) in lateral view. Posterior edges of PAs flat, even posteriorly. Anteriormost SAGs short, dorsolateral and on right side only of 80th and 81st PAs and absent on 82nd; SAGs middorsally complete from 84th PA, ventrally complete from 91st PA. Vent region interrupts last three to four AGs. Vent in circular, fairly discrete disc with 11 denticulations. Single main row of strongly overlapping scales present dorsally in posterior (91st annulus) of body in pocket a little longer than half-length of PA. Scales here longer (1 mm) than wide (0.6 mm).

Strongly bicoloured. In life ( Figure 9 B), dorsum dark lavender with a strong pinkish tinge, pale brown on last tenth of body, darker dorsum colour stops abruptly just approximately halfway down flank, from CM to almost posterior tip. Venter paler lavender with pinkish tinge, somewhat translucent. Head almost same colour as body; TAs in whitish spots that extend back as narrower pale stripes to expected position of eyes; nares, lips and snout tip whitish; lower jaw with whitish V separated from whitish margins of lips. In preservation, colour similar except less lavender and more grey dorsally and more tan ventrally; top of head slightly darker grey than body; pale grey border on lower lip; nares in broad whitish blotches; pale areas at CMs. Additionally, AGs faintly indicated and somewhat variable; pale, giving way to slightly darker very narrow aglandular posterior margins of annuli. Disc surrounding vent unpigmented; unpigmented patch extends in front of disc for a little more than half the length of the disc. Tongue unpigmented.

Variation and additional information from the paratypes and referred specimens. Some morphometric and meristic data are given in Tables 3D and 4 . Noteworthy differences from the type include the following. Top of the head sometimes more convex in lateral view (e.g., BNHS 5495, BNHS 5498, BNHS 5503, BNHS 5504). TAs always close to but may be above or below an imaginary line between nares and CMs, not elevated or visible dorsally in BNHS 5495 and BNHS 5508. Majority have a single, smoothly curved TG on C2. Medial groove between mandibles generally extending posteriorly onto C1, onto C 2 in BNHS 5502. A few AGs more or less complete anteriorly or posteriorly. Anterior AGs not oblique in lateral view. Unpigmented papillae sometimes present anterolaterally on disc. A small, seemingly aglandular area of skin lies anterior and adjacent to disc except in BNHS 5497, BNHS 5507 and SDB.DU 1406. Venter somewhat paler, dark midventral line apparent only on middle third of SDB.DU 5503, very pale blotches anteriorly on venter of BNHS 5505, some specimens with sporadic paler markings on dorsum, with abruptness of transition from dorsal to ventral colour somewhat variable. In BNHS 5504, spots surrounding TAs do not extend back to eye. Pale edges and aglandular darker bands of AGs less obvious in some specimens. Width, distinctiveness and continuity of white V and paler grey V on lower jaw very variable. Some specimens with slightly pale snout tip. Extent, discreteness and clarity of pale spots around nares and those at CMs variable. Narial plugs of most paratypes have an encircling groove anteriorly, lacking groove posteriorly, right plug of BNHS 5500 extends marginally beyond tongue. No substantial gap between tongue tip and IMs. Choanae may be slightly more ovate. Snout projecting in front of mouth from approximately 1.5 to 2 times size of anterior gap between PM and VP series.

Etymology. Named in honour of author RGK’s father Mr Gaiduwan Gaipuizei Kammei (Kohima, Nagaland), in appreciation of him and Kamei’s family who have supported immensely our research in northeast India. The species name gaiduwani is a noun in the genitive case.

Suggested English common name. Gaiduwan’s chikila .

Distribution and natural history. Chikila gaiduwani is currently known from the type locality Teobronggre Coffee Garden, Teobronggre, Tura and surrounding areas in West Garo Hills district and from Nongpoh, Ri Bhoi district of Meghalaya; and Dwarka, Goalpara district and Kanchiguli, Garbhanga, Kamrup district of Assam ( Figure 1 ; Table 1). The known altitudinal range is 86–538 meters asl. The species was common at some localities during the monsoon (late May to mid August). The holotype was collected with a clutch of five eggs. The majority of the collections were from, or adjacent to, agricultural fields (tea garden, abandoned jhum field, paddy field) close to human settlement; a few specimens were collected from fringes of disturbed secondary forest (e.g., ZSI A11536, SDB.DU 1560) from Anogiri 2 and Barkha forest, respectively). BNHS 5507 from Dwarka, Goalpara district, Assam was collected from a roadside marshy area on the fringe of teak plantations.

Remarks. Summary comparisons are provided in Tables 5 and 6 . Beyond the differences given in the diagnosis, the examined material of C. gaiduwani differs from C. alcocki in its moderately pigmented AGs (vs. very faintly marked). Chikila gaiduwani differs from C. darlong in: having relatively more VPs, subequal to or more than PMs (vs. fewer VPs than PMs), and externally invisible eyes. Chikila gaiduwani differs from C. fulleri additionally in: having moderately (vs. very strongly) pigmented AGs, having an extensive (length and breadth) pale eye-TA patch generally encircling and extending beyond the eye, having a disc around the vent with an unpigmented pale patch anterior to the disc, having a VP series forming a gentle arc anteriorly (vs. angulate anteriorly) and in lacking pale blotches on the chin, throat and underside of anteriormost PAs.

The uncorrected mean divergences (16S and cox1 genes) between Chikila gaiduwani and C. alcocki , C. darlong and C fulleri are 9.6%, 6.7% and 8.6%, respectively ( Table 2).

The data suggest also that C. gaiduwani might differ from C. alcocki and C. darlong in having relatively more SAGs and from C. fulleri in having relatively more SAGs, and in attaining a greater maximum length.

Figures

FIGURE 1. Northeast India showing the distribution of the genus Chikila. Positioning of locality dots is approximate; for exact coordinates, see Table 1.

FIGURE 2. DNA phylogeny of Chikila based on the analysis of 1,982 base pairs (bp) of mitochondrial (mt) sequence data comprising a 696 bp long fragment of mt cytochrome oxidase 1 (cox 1), and two (non-overlapping) fragments of mt small subunit ribosomal DNA (16 S) of 463 and 823 bp. Numbers at nodes are support values for Maximum Likelihood (ML) and Bayesian inference (BI) analyses (see Kamei et al. 2012 for details).

FIGURE 3. Midbody (lateral view) of Chikila species skinned and unskinned to show the pigmentation of the annular grooves and of septa in the underlying musculature. A. Chikila alcocki sp. nov. (SDB. DU 1662), B. Chikila darlong sp. nov. (SDB. DU 1695), C. Chikila fulleri (SDB. DU 1304), D. Chikila gaiduwani sp. nov. (SDB. DU 1560). Scale bar: 10 mm.

FIGURE 9. Photographs of profile in life. A. Topotype of Chikila fulleri (SDB. DU 1304), B. Holotype of Chikila gaiduwani sp. nov. with eggs (ZSI A 11543).